A door beam comprising an aluminum alloy extruded member generally has a pair of flanges (an outer flange arranged outward in a vehicle body width direction and an inner flange arranged inward in a vehicle body width direction) and a pair of webs connecting both the flanges. The door beam is arranged between an outer panel and an inner panel of a vehicle door so that a longitudinal direction of the door beam may be directed in an anteroposterior direction of a vehicle body and an end of the door beam is attached to the inner panel directly without a bracket or through a bracket. On this occasion, a partial region of the door beam in the longitudinal direction may sometimes be press-formed beforehand for ensuring a storage space in a door, for the convenience of fastening a bolt, or for another purpose.
Patent Literature 1 describes a method of: press-forming an end of a door beam comprising an aluminum alloy extruded member; buckling a pair of webs outward; opening a bolt hole in the center of the press-formed part in a width direction; and attaching the door beam to an attaching portion of an inner panel with a bolt. In the door beam described in Patent Literature 1, press-forming is applied from an outer flange side toward an inner flange side.
Patent Literature 2 describes a method of, when an end of a door beam comprising an aluminum alloy extruded member is press-formed, curving or bending a pair of webs outward or inward beforehand or forming recesses inside or outside the paired webs so that both the paired webs buckle outward or inward symmetrically. In the example shown in FIG. 5 of Patent Literature 2, press-forming is applied from an outer flange side and an inner flange side toward the center between both the flanges.
Patent Literature 3 describes a method of press-forming an end of a door beam comprising an aluminum alloy extruded member and buckling a pair of webs outward. In the door beam described in Patent Literature 3, press-forming is applied from an outer flange side toward an inner flange side (refer to FIG. 10).
Patent Literature 4 describes a method of press-forming an end of a door beam comprising an aluminum alloy molded member (extruded member) having, in addition to an outer flange and an inner flange, an intermediate flange between both the flanges. Press-forming is applied from an outer flange side toward an inner flange side (refer to FIG. 3).